Add __detail::__chrono_write which formats a chrono object into a
stack buffer via std::format_to_n with _S_empty_fs(), then writes
through __ostream_insert. A non-type template parameter _BufSize
(default 128) allows per-type buffer tuning. Each _BufSize is the
smallest power of two that accommodates the longest possible formatted
output for that type, including error cases. All chrono operator<<
overloads that previously used std::format, std::vformat, or
basic_stringstream now use this helper.
libstdc++-v3/ChangeLog:
* include/bits/chrono_io.h (__formatter_chrono::_S_empty_fs):
Make public.
(__detail::__chrono_write): New function template.
(operator<<): Use __chrono_write consistently for all chrono
types.
Signed-off-by: Anlai Lu <[email protected]>
---
libstdc++-v3/include/bits/chrono_io.h | 244 ++++++--------------------
1 file changed, 52 insertions(+), 192 deletions(-)
diff --git a/libstdc++-v3/include/bits/chrono_io.h
b/libstdc++-v3/include/bits/chrono_io.h
index f8bb485d1..d3740a0e1 100644
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -884,11 +884,13 @@ namespace __format
static constexpr const _CharT* _S_minus_empty_spec = _S_chars + 17;
static constexpr const _CharT* _S_empty_spec = _S_chars + 18;
+ public:
[[__gnu__::__always_inline__]]
static _Dynamic_format_string<_CharT>
_S_empty_fs()
{ return _Dynamic_format_string<_CharT>(_S_empty_spec); }
+ protected:
static constexpr const _CharT* _S_weekdays[]
{
_GLIBCXX_WIDEN("Sunday"),
@@ -3607,6 +3609,30 @@ namespace __detail
}
}
+ // Format into a stack buffer via std::format_to_n with the empty
+ // chrono-spec (_S_empty_fs), then write through __ostream_insert.
+ // The empty spec lets each formatter use its __defSpec, producing
+ // output equivalent to the corresponding operator<<.
+ // _BufSize allows per-type tuning of the stack buffer size.
+ template<size_t _BufSize = 128, typename _CharT, typename _Traits,
+ typename _Arg, typename... _OptLocale>
+ inline basic_ostream<_CharT, _Traits>&
+ __chrono_write(basic_ostream<_CharT, _Traits>& __os,
+ const _Arg& __arg, const _OptLocale&... __loc)
+ {
+ static_assert(sizeof...(_OptLocale) <= 1);
+ constexpr auto __fs
+ = __format::__formatter_chrono<_CharT>::_S_empty_fs;
+ constexpr size_t __bufsize = _BufSize;
+ _CharT __buf[__bufsize];
+ auto __res = std::format_to_n(__buf, __bufsize, __loc...,
+ __fs(), __arg);
+ if (static_cast<size_t>(__res.size) <= __bufsize) [[likely]]
+ return std::__ostream_insert(__os, __buf, __res.size);
+ auto __s = std::format(__loc..., __fs(), __arg);
+ return std::__ostream_insert(__os, __s.data(), __s.size());
+ }
+
} // namespace __detail
/// @endcond
@@ -3629,14 +3655,7 @@ namespace __detail
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const day& __d)
{
- using _Ctx = __format::__format_context<_CharT>;
- using _Str = basic_string_view<_CharT>;
- _Str __s = _GLIBCXX_WIDEN("{:02d} is not a valid day");
- if (__d.ok())
- __s = __s.substr(0, 6);
- auto __u = (unsigned)__d;
- __os << std::vformat(__s, make_format_args<_Ctx>(__u));
- return __os;
+ return __detail::__chrono_write<32>(__os, __d);
}
template<typename _CharT, typename _Traits,
@@ -3657,18 +3676,7 @@ namespace __detail
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const month& __m)
{
- using _Ctx = __format::__format_context<_CharT>;
- using _Str = basic_string_view<_CharT>;
- _Str __s = _GLIBCXX_WIDEN("{:L%b}{} is not a valid month");
- if (__m.ok())
- __os << std::vformat(__os.getloc(), __s.substr(0, 6),
- make_format_args<_Ctx>(__m));
- else
- {
- auto __u = (unsigned)__m;
- __os << std::vformat(__s.substr(6), make_format_args<_Ctx>(__u));
- }
- return __os;
+ return __detail::__chrono_write(__os, __m, __os.getloc());
}
template<typename _CharT, typename _Traits,
@@ -3689,18 +3697,7 @@ namespace __detail
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const year& __y)
{
- using _Ctx = __format::__format_context<_CharT>;
- using _Str = basic_string_view<_CharT>;
- _Str __s = _GLIBCXX_WIDEN("-{:04d} is not a valid year");
- if (__y.ok())
- __s = __s.substr(0, 7);
- int __i = (int)__y;
- if (__i >= 0) [[likely]]
- __s.remove_prefix(1);
- else
- __i = -__i;
- __os << std::vformat(__s, make_format_args<_Ctx>(__i));
- return __os;
+ return __detail::__chrono_write<32>(__os, __y);
}
template<typename _CharT, typename _Traits,
@@ -3721,18 +3718,7 @@ namespace __detail
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const weekday& __wd)
{
- using _Ctx = __format::__format_context<_CharT>;
- using _Str = basic_string_view<_CharT>;
- _Str __s = _GLIBCXX_WIDEN("{:L%a}{} is not a valid weekday");
- if (__wd.ok())
- __os << std::vformat(__os.getloc(), __s.substr(0, 6),
- make_format_args<_Ctx>(__wd));
- else
- {
- auto __c = __wd.c_encoding();
- __os << std::vformat(__s.substr(6), make_format_args<_Ctx>(__c));
- }
- return __os;
+ return __detail::__chrono_write(__os, __wd, __os.getloc());
}
template<typename _CharT, typename _Traits,
@@ -3754,23 +3740,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const weekday_indexed& __wdi)
{
- // The standard says to format wdi.weekday() and wdi.index() using
- // either "{:L}[{}]" or "{:L}[{} is not a valid index]". The {:L} spec
- // means to format the weekday using ostringstream, so just do that.
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- __os2 << __wdi.weekday();
- const auto __i = __wdi.index();
- basic_string_view<_CharT> __s
- = _GLIBCXX_WIDEN("[ is not a valid index]");
- __os2 << __s[0];
- __os2 << std::format(_GLIBCXX_WIDEN("{}"), __i);
- if (__i >= 1 && __i <= 5)
- __os2 << __s.back();
- else
- __os2 << __s.substr(1);
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __wdi, __os.getloc());
}
template<typename _CharT, typename _Traits>
@@ -3778,29 +3748,14 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const weekday_last& __wdl)
{
- // As above, just write straight to a stringstream, as if by "{:L}[last]"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- __os2 << __wdl.weekday() << _GLIBCXX_WIDEN("[last]");
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __wdl, __os.getloc());
}
template<typename _CharT, typename _Traits>
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const month_day& __md)
{
- // As above, just write straight to a stringstream, as if by "{:L}/{}"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- __os2 << __md.month();
- if constexpr (is_same_v<_CharT, char>)
- __os2 << '/';
- else
- __os2 << L'/';
- __os2 << __md.day();
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __md, __os.getloc());
}
template<typename _CharT, typename _Traits,
@@ -3824,12 +3779,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const month_day_last& __mdl)
{
- // As above, just write straight to a stringstream, as if by "{:L}/last"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- __os2 << __mdl.month() << _GLIBCXX_WIDEN("/last");
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __mdl, __os.getloc());
}
template<typename _CharT, typename _Traits>
@@ -3837,17 +3787,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const month_weekday& __mwd)
{
- // As above, just write straight to a stringstream, as if by "{:L}/{:L}"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- __os2 << __mwd.month();
- if constexpr (is_same_v<_CharT, char>)
- __os2 << '/';
- else
- __os2 << L'/';
- __os2 << __mwd.weekday_indexed();
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __mwd, __os.getloc());
}
template<typename _CharT, typename _Traits>
@@ -3855,34 +3795,14 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const month_weekday_last& __mwdl)
{
- // As above, just write straight to a stringstream, as if by "{:L}/{:L}"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- __os2 << __mwdl.month();
- if constexpr (is_same_v<_CharT, char>)
- __os2 << '/';
- else
- __os2 << L'/';
- __os2 << __mwdl.weekday_last();
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __mwdl, __os.getloc());
}
template<typename _CharT, typename _Traits>
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const year_month& __ym)
{
- // As above, just write straight to a stringstream, as if by "{}/{:L}"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- __os2 << __ym.year();
- if constexpr (is_same_v<_CharT, char>)
- __os2 << '/';
- else
- __os2 << L'/';
- __os2 << __ym.month();
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __ym, __os.getloc());
}
template<typename _CharT, typename _Traits,
@@ -3906,12 +3826,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const year_month_day& __ymd)
{
- using _Ctx = __format::__format_context<_CharT>;
- using _Str = basic_string_view<_CharT>;
- _Str __s = _GLIBCXX_WIDEN("{:%F} is not a valid date");
- __os << std::vformat(__ymd.ok() ? __s.substr(0, 5) : __s,
- make_format_args<_Ctx>(__ymd));
- return __os;
+ return __detail::__chrono_write<64>(__os, __ymd);
}
template<typename _CharT, typename _Traits,
@@ -3936,17 +3851,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const year_month_day_last& __ymdl)
{
- // As above, just write straight to a stringstream, as if by "{}/{:L}"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- __os2 << __ymdl.year();
- if constexpr (is_same_v<_CharT, char>)
- __os2 << '/';
- else
- __os2 << L'/';
- __os2 << __ymdl.month_day_last();
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __ymdl, __os.getloc());
}
template<typename _CharT, typename _Traits>
@@ -3954,19 +3859,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const year_month_weekday& __ymwd)
{
- // As above, just write straight to a stringstream, as if by
- // "{}/{:L}/{:L}"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- _CharT __slash;
- if constexpr (is_same_v<_CharT, char>)
- __slash = '/';
- else
- __slash = L'/';
- __os2 << __ymwd.year() << __slash << __ymwd.month() << __slash
- << __ymwd.weekday_indexed();
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __ymwd, __os.getloc());
}
template<typename _CharT, typename _Traits>
@@ -3974,19 +3867,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const year_month_weekday_last& __ymwdl)
{
- // As above, just write straight to a stringstream, as if by
- // "{}/{:L}/{:L}"
- basic_stringstream<_CharT> __os2;
- __os2.imbue(__os.getloc());
- _CharT __slash;
- if constexpr (is_same_v<_CharT, char>)
- __slash = '/';
- else
- __slash = L'/';
- __os2 << __ymwdl.year() << __slash << __ymwdl.month() << __slash
- << __ymwdl.weekday_last();
- __os << __os2.view();
- return __os;
+ return __detail::__chrono_write(__os, __ymwdl, __os.getloc());
}
template<typename _CharT, typename _Traits, typename _Duration>
@@ -3994,7 +3875,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const hh_mm_ss<_Duration>& __hms)
{
- return __os << format(__os.getloc(), _GLIBCXX_WIDEN("{:L%T}"), __hms);
+ return __detail::__chrono_write<64>(__os, __hms, __os.getloc());
}
#if _GLIBCXX_USE_CXX11_ABI || ! _GLIBCXX_USE_DUAL_ABI
@@ -4003,7 +3884,7 @@ namespace __detail
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const sys_info& __i)
{
- return __os << std::format(__os.getloc(), _GLIBCXX_WIDEN("{}"), __i);
+ return __detail::__chrono_write(__os, __i, __os.getloc());
}
/// Writes a local_info object to an ostream in an unspecified format.
@@ -4011,20 +3892,7 @@ namespace __detail
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const local_info& __li)
{
- __os << __format::_Separators<_CharT>::_S_squares()[0];
- if (__li.result == local_info::unique)
- __os << __li.first;
- else
- {
- if (__li.result == local_info::nonexistent)
- __os << _GLIBCXX_WIDEN("nonexistent");
- else
- __os << _GLIBCXX_WIDEN("ambiguous");
- __os << _GLIBCXX_WIDEN(" local time between ") << __li.first;
- __os << _GLIBCXX_WIDEN(" and ") << __li.second;
- }
- __os << __format::_Separators<_CharT>::_S_squares()[1];
- return __os;
+ return __detail::__chrono_write<256>(__os, __li);
}
template<typename _CharT, typename _Traits, typename _Duration,
@@ -4033,8 +3901,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const zoned_time<_Duration, _TimeZonePtr>& __t)
{
- __os << format(__os.getloc(), _GLIBCXX_WIDEN("{:L%F %T %Z}"), __t);
- return __os;
+ return __detail::__chrono_write(__os, __t, __os.getloc());
}
#endif
@@ -4045,16 +3912,14 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const sys_time<_Duration>& __tp)
{
- __os << std::format(__os.getloc(), _GLIBCXX_WIDEN("{:L%F %T}"), __tp);
- return __os;
+ return __detail::__chrono_write<64>(__os, __tp, __os.getloc());
}
template<typename _CharT, typename _Traits>
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const sys_days& __dp)
{
- __os << year_month_day{__dp};
- return __os;
+ return __detail::__chrono_write<32>(__os, __dp);
}
template<typename _CharT, typename _Traits, typename _Duration,
@@ -4090,8 +3955,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const utc_time<_Duration>& __t)
{
- __os << std::format(__os.getloc(), _GLIBCXX_WIDEN("{:L%F %T}"), __t);
- return __os;
+ return __detail::__chrono_write<64>(__os, __t, __os.getloc());
}
template<typename _CharT, typename _Traits, typename _Duration,
@@ -4125,8 +3989,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const tai_time<_Duration>& __t)
{
- __os << std::format(__os.getloc(), _GLIBCXX_WIDEN("{:L%F %T}"), __t);
- return __os;
+ return __detail::__chrono_write<64>(__os, __t, __os.getloc());
}
template<typename _CharT, typename _Traits, typename _Duration,
@@ -4164,8 +4027,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const gps_time<_Duration>& __t)
{
- __os << std::format(__os.getloc(), _GLIBCXX_WIDEN("{:L%F %T}"), __t);
- return __os;
+ return __detail::__chrono_write<64>(__os, __t, __os.getloc());
}
template<typename _CharT, typename _Traits, typename _Duration,
@@ -4202,8 +4064,7 @@ namespace __detail
operator<<(basic_ostream<_CharT, _Traits>& __os,
const file_time<_Duration>& __t)
{
- __os << std::format(__os.getloc(), _GLIBCXX_WIDEN("{:L%F %T}"), __t);
- return __os;
+ return __detail::__chrono_write<64>(__os, __t, __os.getloc());
}
template<typename _CharT, typename _Traits, typename _Duration,
@@ -4228,8 +4089,7 @@ namespace __detail
// 4257. Stream insertion for chrono::local_time should be constrained
requires requires(const sys_time<_Duration>& __st) { __os << __st; }
{
- __os << sys_time<_Duration>{__lt.time_since_epoch()};
- return __os;
+ return __detail::__chrono_write<64>(__os, __lt, __os.getloc());
}
template<typename _CharT, typename _Traits, typename _Duration,
--
2.34.1
